3- Phenyl-2-naphthoquinone

The reaction of 2-anilino-l,4-naphthoquinone 374 with benzoylacetic acid hydrazide gives 3-hydrazino-pyrazolyl derivative 375, that is acetylated to produce 5-[[l,4-dihydro-l,4-dioxo-3-(phenylamino)-2-naphthalenyl]sulfonyl]-3-methyl-6-phenyl-5/7-pyrazolo[5,l-c][l,2,4]triazole 51. This latter derivative is also obtained in 51% yield from reaction of 374 with benzoylacetic acid hydrazide in the presence of a mixture of acetic acid-sodium acetate <2004PS(179)1907> (Scheme 39). 

Naphthoquinone, 2-methyl- 56,70 Neber reaction, 57, 87 Neopentylbromide, 58, 145 NEOPENTYL PHENYL SULFIDE, 58,... 

Heating of a mixture of 2-phenyl-1,4-naphthoquinone (1 eq.) with dimethyl malonate (4 eq.) and manganese(III) acetate (6 eq.) in acetic acid at 80°C for 16 hours gives 1 in 76% yield, and this has been shown to be a general type of reaction for a variety of 2-aryl-l,4-naphthoquinones. 

The nitrogen heterocyclic analogs of quinones, azaquinones, are interesting heterocyclic compounds, but have received only limited attention. In fact, 2-aza-3-phenyl-1,4-naphthoquinone is one of the first examples in the literature (69HCA1810 71TL1621). There are several examples of other hydroxylated derivatives that can exist in several tautomeric forms, and no evidence has been presented that unambiguously establishes which... 

The chemistry of azaquinones centers around the electron-deficient imine double bond. For example, water, methanol, ammonia, methyl-amine, nitromethane, m-xylene, and enamines all add readily to the imine double bond in aza-3-phenyl-l, 4-naphthoquinone. On the other hand azaquinones are also potent dienophiles and thus can function as starting materials for a large variety of highly substituted new heterocyclic compounds. 

Besides alkyloxy carbene complexes, acyloxy carbene complexes have also been proven to be effective in the benzannulation reaction. For example, Yamashita and Ohishi have reported the synthesis of various naphthoquinones in yields of 47-71 % using acetyloxy phenyl chromium carbene complex and terminal alkynes with different alkyl chain lengths [29]. 

Electron-poorer 1,2-dihydrophosphete complexes with alkyl and phenyl substituents at the ring skeleton are inert towards N-phenylmaleimide.443 The reaction of 74 with 1,4-naphthoquinone in benzene at 55°C leads to... 

X = benzoate, picrate, 8-oxyquinolinate, 2-oxy-1,4-naphthoquinonate, p-tert-butyiphenolate, 5-phenyl-2-tetrazoiide, F , BFJ... 

Ab initio and density functional theoretical studies of the 4 -b 2-cycloaddition of 2-azabutadiene with formaldehyde predict a concerted reaction that agrees well with experimental evidence. " The azadiene A-phenyl-l-aza-2-cyanohuta-1,3-diene reacts with electron-rich, electron-poor, and neutral dipolarophiles imder nuld thermal conditions. 5,6-Dihydro-4//-l,2-oxazines have been shown to he useful as synthon equivalents of 2-cyano-l-azabuta-l,3-dienes. The intramolecular Diels-Alder reaction of 1-aza-1,3-butadienes (106) can be activated by a 2-cyano substituent (Scheme 37). Stereoselectivity in the hetero-Diels-Alder reactions of heterobutadienes, nitrosoalkenes, and heterodienophiles has been extensively reviewed. The azadiene l-(t-butyldimethylsilyloxy)-l-azabuta-l,3-diene (107) reacts with halobenzo-quinones, naphthoquinones, and A/ -phenylmaleimide to yield low to good yields of various pyridine heterocycles (108) (Scheme 38). The 4 -b 2-cycloaddition of homophthalic anhydride with A/ -(cinnamylidene)tritylamine produces the 3,4-adduct whereas with A/ -(cinnamylidene)benzylidine the 1,2-adduct is produced. ... 

Synthesis of a tetracyclic analog of 294 is also reported from the anhydride of pyrazine-2,3-dicarboxylic acid and a tetralin derivative under Friedel-Crafts conditions (85JCR(S)338). A representative of the o-quinonoid system (296) was prepared from 2,3-dichloro-1,4-naphthoquinone and o-phenyl-enediamine (63JOC1019). 

With regard to the question of tautomers, the l-phenylazo-2-naphthol/l,2-naphthoquinone phenylhydrazone equilibrium has been studied for a variety of substituted phenyl groups . At least in CDCI3 solution, the difference in stability is small (the parent compound favors the hydrazone by but 4.0 0.3 kJ moR ). 

Concerning l-phenylazo-2-naphthol and 1,2-naphthoquinone 2-phenyl-hydrazone, the chelate structure of which can be influenced by the solvent, reference is made to the work of Burawoy and coworkers. ... 

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